The present invention relates to a monitor device for displaying a front scene of a manned or unmanned moving body running at certain speed. The moving body may be a vehicle or vessel including, although not limited thereto, an automobile, a train, a tram car, a ship, a boat, an aircraft and a roller coaster. The moving body may include a radio-controlled toy plane, motor car and boat.
In such a moving body, it is important to monitor the front scene of the moving body and observe the condition of its running path in order to control the moving body or avoid accident in advance. When a picture of the front scene is taken by a standard lens or fixed focus lens, the image of the far away scene is so small that it is difficult to recognize the condition of the far way scene certainly.
Monitor devices for automobiles have been proposed which take pictures and display images of the lane where the automobile is running, and its surrounding scene. One of the monitor devices disclosed in a Japanese patent No. 3229687, is arranged to take picture of lines on both sides of a traffic lane through a zoom lens with the objective lens being zoomed at a speed higher than the shutter speed such that it is easily and accurately recognized whether the lane is straight or curved at a distance.
This prior art device is useful for the driver to recognize the lane condition at distance, but requires optical zooming mechanism, resulting in increase of mechanical parts. Accordingly, the conventional device has disadvantage in its durability, cost and compactness.
Another monitor device or an image processing device disclosed in a Japanese patent No. 3084208 displays an image of front scene of an automobile, with the image being enlarged by digital zooming such that the zoom ratio is large for a far away scene while the zoom ratio being small for near- by scene. This prior art is designed such that an image of traffic lane lines is detected and the image of the far-away front scene is enlarged in a horizontal direction at a fixed zooming ratio irrespectively of the speed of the automobile. Thus, it will be difficult for the driver to recognize the condition of the far away scene when the automobile is running at high speed.